A wide variety of polymers have been used and suggested for use as membrane materials in membrane processes, such as for use in ultrafiltration, reverse osmosis and electrodialysis membrane processes. Polymer membranes are employed for separating selectively molecules, ions and suspended particles from carrier fluids. Polymer membranes have been employed and suggested for ultrafiltration purposes, for separating proteins and other comparatively large molecules from water, such as, for example, the separation of proteins from lactose and mineral salts in whey, which is a by-product of the dairy industry. In addition, polymer membranes also have been suggested for use in the ultrafiltration of soluble or suspended oils, such as the so-called water-soluble oils, which are often the effluent of operations which employ oils as coolants for high-speed metal-cutting machines.
In separations involving water-based carriers, it is desirable to employ a membrane which has good mechanical strength and which also exhibits desirable hydrophilic properties. This application is directed to a process for preparing improved membranes which exhibit good hydrophilic properties which overcome some of the problems and difficulties of preparing membranes in the prior art, and which improved membranes are useful particularly in the dairy field; for example, for the ultrafiltration of whey, and with oil-water emulsions, such as the ultrafiltration of soluble cutting-oil emulsions.